1. Field of the Invention
The present invention relates generally to solid inductors, and more particularly, to a chip inductor, whose inductance value can be adjusted, using a ceramic magnetic material.
2. Description of the Related Art
A solid inductor formed by passing an inner conductor through a magnetic material such as Ni--Zn ferrite has been conventionally known. This solid inductor is fabricated by forming by the printing process or the like inner electrodes made of Ag, Ag--Pd or the like on green sheets formed by the Doctor blade process or the like, and laminating the green sheets, followed by cofiring.
Examples of a method of adjusting the inductance value of such a solid inductor so as to be lower include a method of subjecting a chip inductance element to laser irradiation or machining to cut a part thereof.
Furthermore, examples of a method of adjusting the inductance value of such a solid inductor so as to be higher include a method of applying paste made of ferrite to the periphery of a chip inductance element to increase the volume of a magnetic material.
However, the solid inductor whose inductance value is adjusted in each of the above described methods has the disadvantage in that the shape thereof is changed from the shape of the solid inductor before the adjustment, so that the treatment thereof is complicated. In addition, it also has the disadvantage in that large numbers of solid inductors cannot be produced in each of the above described methods, to raise costs.
Additionally, in the conventional solid inductor, the inner electrodes are formed on the green sheets by the printing process or the like, and the green sheets are laminated, followed by cofiring, as described above. Accordingly, the sintering temperature must be significantly lower than that of the conventional ferrite core, so that the density of a sintered body becomes low depending on materials used. Consequently, the solid inductor is inferior in resistance to humidity. Therefore, the conventional solid inductor has the disadvantage in that when a magnetic material after sintering is dipped in a plating solution so as to form outer electrodes, a metal for plating grows on the surface of the magnetic material to which the inner electrodes are diffused, or the plating solution enters the magnetic material, so that the inner electrodes corrode. In addition, it also has the disadvantage in that the plating solution is exuded from the magnetic material after the plating, so that a substrate corrodes, for example.